Miniature isometric joystick

• US 5,541,622 A
• Filed: 08/09/1993
• Issued: 07/30/1996
• Est. Priority Date: 07/24/1990
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Incontrol Solutions, Inc.
• Inventors: Engle, T. Scott, Franz, Patrick J.
• Primary Examiner(s): SARAS, STEVEN J
• Application Number:
  US08/104,777
• Time in Patent Office: 1,086 Days
• Field of Search: 345/168, 345/172, 345/184, 345/161, 345/157, 345/156, 200/6 A, 200/5 A, 200/511, 200/513, 338/114, 338/99, 338/128, 74/471 XY, 341/34, 341/27, 341/20, 341/22
• US Class Current: 345/161
• CPC Class Codes: G05G 2009/04762 Force transducer, e.g. strain gauge
• CPC Class Codes: G05G 9/047 the controlling member being movable by hand about orthogonal axes, e.g. joysticks for switches H01H25/04
• CPC Class Codes: G06F 3/0213 Arrangements providing an integrated pointing device in a keyboard, e.g. trackball, mini-joystick for pointing devices integrated in a laptop computer G06F1/169; joysticks G05G9/047; constructional details of pointing devices G06F3/033
• CPC Class Codes: G06F 3/023 Arrangements for converting discrete items of information into a coded form, e.g. arrangements for interpreting keyboard generated codes as alphanumeric codes, operand codes or instruction codes
• CPC Class Codes: G06F 3/0338 with detection of limited linear or angular displacement of an operating part of the device from a neutral position, e.g. isotonic or isometric joysticks
• CPC Class Codes: H01H 13/70 having a plurality of operating members associated with different sets of contacts, e.g. keyboard mounting together a plurality of independent switches H02B
• CPC Class Codes: H01H 13/785 characterised by the material of the contacts, e.g. conductive polymers
• CPC Class Codes: H01H 13/807 characterised by the spatial arrangement of the contact sites, e.g. superimposed sites
• CPC Class Codes: H01H 2003/0293 with an integrated touch switch
• CPC Class Codes: H01H 2201/02 Piezo element
• CPC Class Codes: H01H 2201/036 Variable resistance
• CPC Class Codes: H01H 2221/012 Joy stick type
• CPC Class Codes: H01H 2225/018 Consecutive operations
• CPC Class Codes: H01H 2225/03 Different type of switches
• CPC Class Codes: H01H 2239/006 Containing a capacitive switch or usable as such
• CPC Class Codes: H01H 2239/052 Strain gauge
• CPC Class Codes: Y10T 74/20201 Control moves in two planes

Abstract

A miniature isometric joystick is disclosed for receiving manual user input to effect directional control such as controlling cursor movement on a computer display screen or controlling movement of an apparatus such as a machine or robot. The joystick is arranged to fit between the existing keys in a computer keyboard. The joystick includes a preloading spring for compressing the assembly together, thereby biasing the force sensors so as to neutralize manufacturing variations and control electrical and mechanical null zones. An integrated switch is provided in the joystick for detecting an external force applied by the user'"'"'s fingertip. The switch unobtrusively detects when a user is pointing, thereby allowing a control system to measure pointing system bias signals while the user is not pointing. This permits the control system to automatically correct for drift, without requiring additional keyboard space for a separate switch to enable the pointing device.

Claims

1. A miniature isometric joystick apparatus comprising:

a generally flat, rigid base plate;

generally planar force-sensing means disposed in substantially parallel contact with the base plate;

an actuator assembly registered over the force-sensing means for transmitting forces applied to the actuator assembly by a user to the force-sensing means;

preload means for urging the actuator assembly and the base plate together so as to maintain the actuator plate in constant contact with the force-sensing means so that the force-sensing means is responsive to an initial force applied to the actuator assembly, thereby eliminating a null zone of operation;

integrated switch means coupled to the actuator assembly for detecting presence of the user'"'"'s fingertip contacting the actuator assembly;

means responsive to the integrated switch means for reading the force sensing means while the integrated switch means is not activated to acquire bias force information; and

means responsive to the integrated switch means for reading the force sensing means while the integrated switch means is activated to acquire pointing force information.

2. A joystick apparatus according to claim 1 wherein the actuator assembly includes an upright, rigid shaft and an actuator plate coupled to a bottom end of the shaft;

and the integrated switch means comprises;

a pliable, hollow cap covering a top end of the shaft, the cap having an electrically conductive interior surface, and being coupled to the shaft along a peripheral edge of the cap; and

an electrically conductive interior electrode overlying a central portion of the top end of the shaft and spaced apart from the said interior surface of the cap so as to permit generally downward deformation of the cap for establishing contact between the said interior surface and the interior electrode whenever pressure is applied to the actuator assembly through the cap by the user'"'"'s finger;

the interior electrode having a depending portion extending through the shaft for electrical connection of the switch means.

3. A joystick apparatus according to claim 1 wherein:

the actuator assembly includes an upright, rigid shaft and an actuator plate coupled to a bottom end of the shaft; and

the shaft is sized and shaped so as to fit in between existing adjacent keycaps of a standard computer keyboard without contacting any of the keycaps.

4. A joystick apparatus according to claim 1 further comprising a resilient joystick tip coupled to the top end of the actuator assembly, the tip being coupled to the switch means for actuating the switch means responsive to deformation of the tip by the user'"'"'s fingertip.

5. A joystick apparatus according to claim 1 wherein the switch means includes a capacitive switch coupled to a top end of the actuator assembly for detecting a user'"'"'s fingertip contacting the top end of the actuator assembly.

6. A miniature isometric joystick apparatus according to claim 1

wherein a top region of the actuator assembly is sized and tapered so as to fit between adjacent keycaps of a keyboard so as to permit use of the joystick apparatus without contacting the adjacent keycaps;

and wherein only a top end of the actuator assembly extends above the adjacent keycaps, and the said integrated switch means is integrated with the top end of the actuator assembly so the integrated switch means detects presence of the user'"'"'s fingertip at all times that a user is pressing on the joystick apparatus.

7. A joystick apparatus according to claim 1 wherein:

the actuator assembly includes an upright, rigid shaft and an actuator plate coupled to a bottom end of the shaft;

the actuator assembly further includes a tip coupled to a top end of the shaft for receiving the user'"'"'s fingertip;

the integrated switch means is coupled to the tip to detect when a user is operating the joystick; and

the shaft and tip are sized to extend above the keys of a keyboard when the joystick apparatus is installed in the keyboard, thereby allowing manipulation of the joystick apparatus by a user without pressing any of the keyboard keys.

8. A joystick apparatus according to claim 1 wherein:

the preload means includes a spring;

the force sensing means includes three force sensing elements symmetrically arranged about a center axis of the apparatus;

the actuator means includes a generally planar actuator plate overlying the force sensing means, the actuator plate having three actuator surfaces, each actuator surface protruding toward a respective one of the force sensing elements; and

the integrated switch means is positioned along the center axis.

9. A joystick apparatus according to claim 1 wherein the actuator surfaces comprise rubber bumps coupled to the actuator plate.

10. A joystick apparatus according to claim 1 wherein:

the preload means includes a spring disposed below the base plate and the base plate includes means defining a central aperture; and

further comprising fastening means extending through the central aperture for connecting the spring to the actuator assembly so as to compress the spring, thereby preloading the force-sensing means while allowing limited rocking motion of the actuator assembly responsive to external force applied to the actuator assembly.

11. A joystick comprising:

a generally flat, rigid reference plate;

generally planar force sensing means, disposed in parallel contact on top of the reference plate and having a plurality of force sensing elements positioned in a predetermined pattern, for sensing force applied to the sensing elements; and

actuator means disposed on top of the force sensing means and having a plurality of actuator surfaces protruding toward the force sensing means, each of the actuator surfaces contacting a respective one of the force sensing elements for supporting the actuator means and for transmitting to the corresponding force sensing element an external force applied to the actuator means by a user;

the actuator means being supported solely by the force sensing elements so that substantially all forces applied by the user to the actuator means are transmitted to the force sensing means;

means for pre-loading the force sensing elements so that each force sensing element provides a respective predetermined output signal when no external force is being applied to the actuator means by the user; and

switch means coupled to the actuator means so as to detect presence of a user'"'"'s fingertip contacting the actuator means.

12. In a computer keyboard having a baseplate and an array of existing keyswitches mounted on the baseplate, a method of acquiring electrical signals responsive to forces applied by a user for controlling cursor movement on a visual display screen, the method comprising:

selecting a location on the baseplate intermediate the existing keyswitches;

providing a plurality of force sensing elements, each such element having an electrical characteristic that varies in response to force applied to said element;

symmetrically arranging the force sensing elements around the selected location, so that the force sensing elements do not interfere with operation of the existing keyswitches;

providing an actuator assembly positioned on top of the force sensing elements and supported solely by the force sensing elements, the actuator assembly having a shaft extending upward from the selected location in between the existing keyswitches for operation by the user'"'"'s fingertip;

maintaining a pre-loading force on the actuator assembly generally along a vertical axis normal to the baseplate so as to force the actuator assembly against all of the force sensing elements in the absence of an external force on the shaft;

providing an integrated switch coupled to a top end of the shaft for detecting a force applied by the user'"'"'s fingertip contacting the shaft; and

sizing and arranging the shaft relative to the existing keyswitches so that the shaft is substantially inaccessible to the user except through the top end, thereby substantially preventing the user from applying force to the actuator assembly without actuating the integrated switch.

13. A method according to claim 12 further comprising the step of selecting the pre-loading force so as to bias the force sensing elements to a desired intermediate operating point, so that an external deflecting force applied to the shaft angularly offset from the Z axis increases the force on at least one of the force sensing elements and decreases the force on an opposing element, thereby providing differential electrical signals for cursor control in response to said deflection force.

14. In a computer keyboard having a baseplate and an array of existing keyswitches mounted on the baseplate, a method of acquiring electrical signals responsive to forces applied by a user for controlling cursor movement on a visual display screen, the method comprising:

selecting a location on the baseplate intermediate the existing keyswitches;

providing a plurality of force sensing elements, each such element having an electrical characteristic that varies in response to force applied to said element;

symmetrically arranging the force sensing elements around the selected location, so that the force sensing elements do not interfere with operation of the existing keyswitches;

providing an actuator assembly positioned on top of the force sensing elements and supported solely by the force sensing elements, the actuator assembly having a shaft extending upward from the selected location in between the existing keyswitches for operation by the user'"'"'s fingertip;

maintaining a pre-loading force on the actuator assembly generally along a vertical axis normal to the baseplate so as to force the actuator assembly against all of force sensing elements in the absence of an external force on the shaft;

providing an integrated switch having a tip for activating the switch and coupled to a top end of the shaft for detecting presence of the user'"'"'s fingertip contacting the shaft;

substantially covering the top end of the shaft with the tip; and

sizing and arranging the shaft relative to the existing keyswitches so that the shaft is substantially inaccessible to the user except through the tip, thereby ensuring that the user activates the integrated switch whenever the user applies force to the actuator assembly;

while the user'"'"'s fingertip is not detected, measuring the force sensing elements to acquire an indication of applied force, thereby acquiring bias force information;

while presence of the user'"'"'s fingertip is detected, measuring the force sensing elements to acquire an indication of applied force, thereby acquiring pointing force information; and

combining the bias force information and the pointing force information to form directional data for controlling cursor movement on the visual display screen.

15. A miniature isometric joystick apparatus comprising:

a generally flat, rigid base plate;

generally planar force-sensing means disposed in substantially parallel contact with the base plate;

an actuator assembly registered over the force-sensing means for transmitting forces applied to the actuator assembly by a user to the force-sensing means;

preload means for urging the actuator assembly and the base plate together so as to maintain the actuator plate in constant contact with the force-sensing means so that the force-sensing means is responsive to an initial force applied to the actuator assembly, thereby eliminating a null zone of operation; and

integrated switch means coupled to the actuator assembly for detecting presence of the user'"'"'s fingertip contacting the actuator assembly;

wherein a top region of the actuator assembly is sized so as to fit between adjacent keycaps of a standard keyboard so as to permit use of the joystick apparatus without contacting the adjacent keycaps; and

measurement means coupled to the force sensors and coupled to the integrated switch means for acquiring pointing force information while the integrated switch means detects presence of the user'"'"'s fingertip contacting the actuator assembly and for acquiring bias force information while the integrated switch means does not detect presence of the user'"'"'s fingertip contacting the actuator assembly.

16. In a computer keyboard having a baseplate and an array of existing keyswitches mounted on the baseplate, a method of acquiring electrical signals responsive to forces applied by a user for controlling cursor movement on a visual display screen, the method comprising:

selecting a location on the baseplate intermediate the existing keyswitches;

providing a plurality of force sensing elements, each such element having an electrical characteristic that varies in response to force applied to said element;

symmetrically arranging the force sensing elements around the selected location, so that the force sensing elements do not interfere with operation of the existing keyswitches;

providing an actuator assembly positioned on top of the force sensing elements and supported solely by the force sensing elements, the actuator assembly having a shaft extending upward from the selected location in between the existing keyswitches for operation by the user'"'"'s fingertip;

providing an integrated switch having a tip for activating the switch and coupled to a top end of the shaft for detecting presence of the user'"'"'s fingertip contacting the shaft;

substantially covering the top end of the shaft with the tip; and

sizing and arranging the shaft relative to the existing keyswitches so that the shaft is substantially inaccessible to the user except through the tip, thereby ensuring that the user activates the integrated switch whenever the user applies force to the actuator assembly;

while the user'"'"'s fingertip is not detected, measuring the force sensing elements to acquire bias force information;

while presence of the user'"'"'s fingertip is detected, measuring the force sensing elements to acquire an indication of applied force, thereby acquiring pointing force information; and

combining the bias force information and the pointing force information to form directional data for controlling cursor movement on the visual display screen.